Tectonic landforms and a fault outcrop in the Fujikawa Valley, Central Japan

Abstract

　 We found several faulted landforms and an active fault outcrop around the Minobu fault, Yamanashi Pref., central Japan. The Neguma fault may be a reverse fault dislocating a fan surface (not dated) ca. 13 m vertically. Fluvial terrace surfaces at Wada are classified into W1 to W5 surfaces in descending order. It is probable that the W3 surface was formed in the period of MIS 5 to MIS 4. The Wada fault cuts the Neogene and the overlying gravel distributed in almost the same height with the W3 surface. The dip and strike of the fault plane are N5゜E and 50-60゜W, respectively. The striations are plunging to the south at an angle of ca. 20 degree and blow. The relative vertical component is upthrown on the east side. These structures are indicative of left-lateral movement. The maximum accumulated left-lateral slip since MIS 5 to MIS 4 is 100 m at least.